Wireless Local Area Networks (WLANs) are becoming very popular today whereby the transceiver may be small and the user no longer needs to be tied to an Ethernet cable. It is also desirable that the communications device such as a wireless transceiver be a mobile battery powered device. The transceiver may be in the form of a lap top computer or a cell phone.
Because the transceiver is often used without connection to a power source through a power cord, the transceiver is therefore subject to battery drain that limits its use away from a power source. Extending the time period between battery charges is of key importance to continued communications. Various subsystems of a battery powered device may place heavier demands upon battery resources than others. When the battery powered device employs a wireless transceiver to transmit and receive data, the transceiver typically consumes significant quantities of battery power which impacts battery life.
In order to increase the overall battery life of such transceivers, power management schemes have been utilized where the communications device enters a sleep mode where only the basic device functions such as system clock, timers, interrupts, etc. are operational. In this mode the device can neither transmit nor receive information and therefore can not perform any communication activities.
It is desirable to provide a power management system that does not impair the communications capability. Power consumption has become a major performance factor for the WLAN chipset. An important task of the IEEE 802.11a/g standard is the power consumption.